Effect of neutron irradiation embrittlement on cyclic hardening behavior of core shroud assembly in pressurized water reactor under beyond-design basis earthquake

2019 ◽  
Author(s):  
Jong-Sung Kim ◽  
Jun-Min Seo ◽  
Yun-Jae Kim ◽  
Young-In Choi ◽  
Chang-Sik Oh ◽  
...  
Keyword(s):  
Neutron Irradiation ◽  
Cyclic Hardening ◽  
Pressurized Water Reactor ◽  
Irradiation Embrittlement ◽  
Pressurized Water ◽  
Water Reactor ◽  
Hardening Behavior ◽  
Design Basis ◽  
Core Shroud

Bayesian Analysis of Japanese Pressurized Water Reactor Surveillance Data for Irradiation Embrittlement Prediction

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Hisashi Takamizawa ◽  
Yutaka Nishiyama
Keyword(s):  
Statistical Analysis ◽  
Neutron Fluence ◽  
Correlation Method ◽  
Credible Interval ◽  
Pressurized Water Reactor ◽  
Irradiation Embrittlement ◽  
Pressurized Water ◽  
Water Reactor ◽  
Cu Content ◽  
Input Variables

Abstract The goal of this study was to identify the chemical component variables that should be used in irradiation embrittlement prediction and to determine the uncertainty of prediction of irradiation embrittlement of reactor pressure vessel (RPV) steels. To this end, statistical analysis using a Bayesian nonparametric (BNP) method was performed for Japanese pressurized water reactor (PWR) surveillance test data whose neutron fluence ranged from 3 × 1018 to 1.2 × 1020 n/cm2 (E > 1 MeV). The BNP method is a machine learning statistical method that takes the complexity and uncertainty of input variables into account. Statistical analysis using an index to select the most suitable combination of input variables revealed that four variables, namely, neutron fluence and Cu, Ni, and Si contents, were the most effective combination for embrittlement prediction. Cu content had the largest effect on the degree of embrittlement, followed by Ni and Si, in that order. The shift in the reference nil-ductility temperature (ΔRTNDT) was also calculated using the probability distribution obtained by the BNP method. The overall standard deviation of the residuals between the calculated and measured values of ΔRTNDT was 8.4 °C, which was comparable to that of the current Japanese embrittlement correlation method (JEAC4201-2013). The 95% credible interval (CI) of the posterior distribution of ΔRTNDT (i.e., the range in which data can exist when the uncertainty of input data is taken into consideration) calculated by the BNP method was identical to or smaller than the margin in the current Japanese embrittlement correlation method described in JEAC4201-2013. This result indicates that an adequate margin is provided in JEAC4201-2013.

scholarly journals Methodology for Stress-Controlled Fatigue Test Under In-Air and Pressurized Water Reactor Coolant Water Condition and to Evaluate the Effect of Pressurized Water Reactor Water and Loading Rate on Ratcheting

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Bipul Barua ◽  
Subhasish Mohanty ◽  
Joseph T. Listwan ◽  
Saurindranath Majumdar ◽  
Krishnamurti Natesan
Keyword(s):  
Loading Rate ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Fatigue Loading ◽  
Stress Rate ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Water Test ◽  
Reactor Coolant Water

This work investigates the behavior of 316 stainless steel (SS) under stress-controlled low cycle fatigue loading. Several fatigue experiments are conducted under different environment such as in air at 300 °C and primary loop water conditions for a pressurized water reactor (PWR). Two different loading conditions are also employed to examine the effect of stress rate on material hardening and ratcheting. During PWR water test, actuator position measurements are used to determine the strain of the specimen. Under PWR environment, 316 SS is found to ratchet to a significantly greater degree compared with in air. At slow stress rate, higher amount of cyclic hardening is observed in 316 SS, and slow stress rate increases the rate of ratcheting. Results also indicate that 316 SS exhibits asymptotic strain response at higher stress loading which can cause material to behave very differently under same stress cyclic loading.

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